[Generation] AdditionalFiles should not be removed if not added by uno

[jeromelaban]

Discussed in #8175

^{Originally posted by HavenDV February 23, 2022}
I noticed that the Uno package started blocking the use of third-party generators. In my case, I was generating View code behind constructor code in my test project.
Is this a bug or is it a special behavior to limit the possible problems of using other generators in most cases? In second case, just need to create a library that will call these generators and use it already in Uno

I assume it is caused by this code

uno/src/SourceGenerators/Uno.UI.SourceGenerators/Content/Uno.UI.SourceGenerators.props

Lines 362 to 363 in 2ed9559

	<_AdditionalFilesCleanup Include="@(AdditionalFiles)" />
	<AdditionalFiles Remove="@(_AdditionalFilesCleanup)" />

P.S. I did not find any changes in the code that would explicitly prohibit the use of other generators. But I still can't achieve using another generator in a project with Uno.UI.WebAssembly. This may be related to dotnet updates to 6.0.2 or VS to 17.2 preview

Repro:
ratbuddyssey-master.zip

1. Build Ratbuddyssey.Apps.Uno.WebAssembly. The generator will not show the generated file (it should appear if at least one AdditionalFile exists at the time of generation)

2. This is not a bug related to the generation order. If you remove Visible="False" then you can see that AdditionalFile exists before the start of build. But it seems then some MSBuild code removes AdditionalFile at one of the stages of preparation. 3. ViewBase code is generated in another library (Ratbuddyssey.Apps.Uno.Core.Standard) and available for Uno generator

[HavenDV]

uno/src/SourceGenerators/Uno.UI.SourceGenerators/Content/Uno.UI.SourceGenerators.props

Lines 362 to 364 in 2ed9559

	<_AdditionalFilesCleanup Include="@(AdditionalFiles)" />
	<AdditionalFiles Remove="@(_AdditionalFilesCleanup)" />
	<AdditionalFiles Condition="'@(_AdditionalFilesCleanup)'!=''" Include="@(_AdditionalFilesCleanup->'$([System.IO.Path]::GetFullPath('%(_AdditionalFilesCleanup.Identity)'))')" />

The problem is because this code clears the metadata for AdditionalFiles. The fix is either by removing this code (I need to know why the full path is being used) or by moving the metadata on cleanup

[HavenDV]

I guess this can be solved with something like

<AdditionalFiles>
        <Identity>$([System.IO.Path]::GetFullPath('%(AdditionalFiles.Identity)'))</Identity>
</TestItemGroup>

But I need to check if this will update the FullPath and other metadata.

[HavenDV]

Everything turned out to be not so simple. Even if these three lines are removed, msbuild cannot merge the metadata for AdditionalFiles that were specified with a relative path and the metadata for AdditionalFiles with an absolute path, even if the end result is the same. Only the metadata for the AdditionalFiles that were added last will remain.
Therefore, in order to preserve the metadata for existing AdditionalFiles, we need to check for existence and separate behavior for each case.

By testing on a real project with _InjectAdditionalFiles override so far I've come to this solution. I need to look at it with fresh eyes to make sure that everything is normal (this works correctly)

<Project>

  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk.Web" />
  
  <!-- Project code -->

  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk.Web" />
  
  <Target Name="_InjectAdditionalFiles" BeforeTargets="GenerateMSBuildEditorConfigFileShouldRun;GenerateMSBuildEditorConfigFileCore" DependsOnTargets="_FillSourceGeneratorItemGroups">

    <ItemGroup Label="Include new additional files">
      <_ExistingAdditionalFiles Include="%(AdditionalFiles.FullPath)" />
      <AdditionalFiles Include="%(Page.FullPath)" SourceItemGroup="Page" Exclude="@(_ExistingAdditionalFiles)" />
      <AdditionalFiles Include="%(ApplicationDefinition.FullPath)" SourceItemGroup="ApplicationDefinition" Exclude="@(_ExistingAdditionalFiles)" />
      <AdditionalFiles Include="%(PRIResource.FullPath)" SourceItemGroup="PRIResource" Exclude="@(_ExistingAdditionalFiles)" />
      <AdditionalFiles Include="%(TSBindingAssemblySource.FullPath)" SourceItemGroup="TSBindingAssemblySource" Exclude="@(_ExistingAdditionalFiles)" />
    </ItemGroup>
    
    <PropertyGroup>
      <_Pages>@(Page)</_Pages>
      <_ApplicationDefinitions>@(ApplicationDefinition)</_ApplicationDefinitions>
      <_PRIResources>@(PRIResource)</_PRIResources>
      <_TSBindingAssemblySources>@(TSBindingAssemblySource)</_TSBindingAssemblySources>
    </PropertyGroup>
    
    <ItemGroup Label="Add SourceItemGroup metadata to existing additional files">
      <AdditionalFiles SourceItemGroup="Page" Condition="$([System.String]::new('$(_Pages)').Contains('%(AdditionalFiles.FullPath)'))" />
      <AdditionalFiles SourceItemGroup="ApplicationDefinition" Condition="$([System.String]::new('$(_ApplicationDefinitions)').Contains('%(AdditionalFiles.FullPath)'))" />
      <AdditionalFiles SourceItemGroup="PRIResource" Condition="$([System.String]::new('$(_PRIResources)').Contains('%(AdditionalFiles.FullPath)'))" />
      <AdditionalFiles SourceItemGroup="TSBindingAssemblySource" Condition="$([System.String]::new('$(_TSBindingAssemblySources)').Contains('%(AdditionalFiles.FullPath)'))" />
    </ItemGroup>

  </Target>

</Project>